However it's a great idea, go for it!
A youtube crawler.
But yeah, I'd love the idea, it depends on whether big G is ok to have someone else doing what they could be doing but aren't to increase their ad money.
The trick is to do as little as necessary to provide the most essential end result in isolation.
You have big dreams, scale them back to this one idea, you are curating YouTube (or other stream source) content.
You cannot possibly process all YouTube content. Consider an interface like invidious with an alt button that queues the video, and from that precache clusters of recommendations, and then promote these to the similar interest group.
Whatever you do, curation is always a prosperous middle layer if you get the right niche interests.
sigwinch•1h ago